Au-Nanoparticle-Array/Aligned-Ag-Nanowire-Based Flexible Dual Plasmonic Substrate for Sensitive Surface-Enhanced Raman Scattering Detection

The fabrication of flexible surface-enhanced Raman scattering (SERS) substrates for sensitive detection on uneven or irregular surfaces is challenging. In this study, a flexible dual plasmonic SERS (FDPS) substrate rationally constructed using Au nanoparticle (AuNP) arrays/aligned Ag nanowires (AgNWs) and elastic polyurethane (PU) is demonstrated. It exhibits high sensitivity (detection limit of 10⁻⁸ m for melamine and 10⁻¹⁰ m for malachite green) and excellent reproducibility. The well-designed structure of AuNP arrays/aligned AgNWs fabricated using block copolymer self-assembly and oil–water–air interfacial self-assembly successfully enhances the electromagnetic field through plasmonic coupling. In addition, the FDPS substrate retains a high SERS sensitivity after exposure to air at room temperature for 30 days because of the high stability of AuNP arrays and antioxidation characteristic of the PU covered on the aligned AgNWs. Even after undergoing stretching, bending, and twisting for 100 cycles, the FDPS substrate maintains a stable SERS activity owing to the introduction of the elastic PU. This study demonstrates a potential application of SERS detection under practical conditions for irregular surfaces and may be helpful in the development of flexible sensors.     

基于多域特征提取和深度学习的声源被动测距*

由于实际海洋环境中存在大量的非高斯噪声,一些基于高斯假设的传统去噪方法在实际海洋环境中性能下降甚至失效。针对非高斯噪声,如α稳定分布噪声、非平稳行船噪声下的脉冲信号的去噪与重构,该文提出一种基于深度学习的方法。去噪模型首先通过学习带噪信号短时傅里叶变换谱与残差谱之间的映射关系以去除环境噪声,之后对去噪信号的时频谱进行逆变换重构脉冲信号。仿真实验结果表明,深度学习模型在非高斯噪声环境下脉冲信号的去噪与重构任务中有着良好的表现,在实测样本上也表现出良好的泛化性,体现了一定的工程应用价值。     

Syntheses,Structures, and Photophysical Properties of Two Coordination Polymers Based on 2,3‐Dioxo‐1,2,3,4‐tetrahydroquinoxaline‐6‐carboxylic Acid

Two complexes based on the ligand 1,4‐dihydro‐2,3‐quinoxalinedione, namely [Mn(H₂L)₂(H₂O)₂]_n ( 1 ) and {[Zn₂(H₂L)₂(tz)₂] · 5H₂O}_n ( 2 ) (H₃L = 2,3‐dioxo‐1,2,3,4‐tetrahydroquinoxaline‐6‐carboxylic acid, Htz = 1,2,4‐triazole) were hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, as well as single‐crystal and powder X‐ray diffraction. Complex 1 exhibited a 1D comb‐like chain formed by H₂L^– anions linking Mn^II ions, whereas complex 2 was a 2D layer‐like structure with square‐shaped windows and outstretched arms built by combination of H₂L^– and tz^– ligands with Zn^II ions. The adjacent chains or layers connected with each other by intermolecular hydrogen bonding and π–π stacking to further extend to a 3D supermolecular framework. In addition, the thermal stabilities, luminescence properties, and optical energy gap of 1 and 2 were investigated in detail.     

Determination of Rosiglitazone by Direct Analysis in Real-Time Mass Spectrometry

The determination of rosiglitazone in dietary supplements by direct analysis in real-time mass spectrometry normally provides low repeatability. The [M+H]⁺ signal sharply decreased in the presence of strong-base and weak-acid ionic compounds because rosiglitazone decomposition occurred due to the hydrolysis of strong-base and weak-acid anions. The repeatability was improved and the influence of ionic compounds was minimized by the use of pioglitazone as an internal standard. Orbitrap mass spectrometry was used to provide high resolution in which isotopic interferences from M?+?1 of pioglitazone upon M of rosiglitazone were eliminated. This approach was used to determine rosiglitazone in tablet and dietary supplements in 1?min per sample.     

Enhanced Photocatalytic Degradation of Methylene Blue over Hexagonal WO<Subscript>3</Subscript>/Graphene under Visible-Light Irradiation

A series of composites containing hexagonal tungsten trioxide (h-WO₃) and reduced graphene oxide (rGO) sheets are synthesized via a modified one-step hydrothermal route without assisted additive. The composites are characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and UV-vis absorption spectroscopy. The new procedure made it possible to increase the reduction degree of GO. Based on the evidence presented hexagonal WO₃ grows on the surface of graphene through chemical interactions with the surface. The visible-light photocatalytic degradation of methylene blue shows that the h-WO₃/rGO composites exhibit superior photocatalytic performance of 96% with a maximum degradation rate achieved under visible-light irradiation for 6 h. The speculations concerning the mechanism of photocatalytic reactions are discussed. The improved photocatalytic activity can be accounted for by the increased adsorption toward chemical species, the enhanced light absorption and an efficient separation of photogenerated electron-hole pairs and transfer of charge carriers.     

Biomimetic superhydrophobic UHMWPE/nanosilica films with different sticky behavior on several metals

A kind of organic–inorganic composite film with biomimetic superhydrophobic performance was prepared on several metals including steel, aluminum, and copper. The organic matrix was ultrahigh‐molecular‐weight polyethylene (UHMWPE), and the inorganic filler was nanosilica. Scanning electron microscope observation indicated addition of nanosilica greatly changed the topography of the UHMWPE film. Special convexities were formed on the surfaces of the composite films, which made the composite films rougher than that of pure UHMWPE film. The nanosilica randomly scattered on the surface of the convexities and formed hierarchical structure similar to that of some plant leaves with superhydrophobic characteristics. Interestingly, it was found that there were remarkable differences between the sliding angles (SA) of water droplet on the composite films on different metals although the contact angles (CA) of water droplet on these films were quite close. The CA on the composite films on steel was about 157°, and the SA was larger than 90°, which demonstrated obvious superhydrophobic and sticky characteristic. But to the films on aluminum and copper, the CAs on them were larger than 160° and the SAs were between 3° and 4°, which meant excellent superhydrophobic and roll‐off performance. Scanning electron microscope observation indicated that there were some micro‐orifices in the film on steel and these micro‐orifices were connected to some extent. It was believed that these micro‐orifices provided capillary force and restrained sliding of water droplet. A sticky model based on capillary mechanism was proposed. Copyright © 2017 John Wiley & Sons, Ltd.     

Characterisation and effect of polymer network deformation in reverse-mode polymer-stabilised cholesteric texture

In reverse-mode polymer-stabilised cholesteric texture (PSCT), the dynamic response is derived from local director reorientation governed by dielectric coupling effect/self-assembly and polymer network deformation. A double exponential rise/decay model is proposed to investigate the underlying physical mechanisms. Through simulation of the transient rise and decay processes, the polymer network deformation in PSCT can be quantitatively evaluated. Less deformation and faster restoration speed of the polymer network can suppress hysteresis. These results provide useful guidelines for future PSCT fabrication and performance optimisation.     

Polymer network liquid crystal grating/Fresnel lens fabricated by holography

In this article, polymer network liquid crystal (PNLC) grating/Fresnel lens is fabricated by holography. The exposure light pattern for the grating is obtained by interfering two planar wave fronts, while the Fresnel pattern is achieved by interfering a planar wave front and a spherical wave front. Owing to the alignment effect and anchoring power of polymer network, the holographic PNLC grating achieves improved diffraction efficiency, and remarkably reduced operation voltage (reduced by 80%) compared with holographic polymer-dispersed-liquid-crystal and holographic polymer-stabilised blue-phase liquid-crystal gratings, while maintaining submillisecond response. Moreover, it achieves high spatial frequency with a 2-μm grating period, thanks to the holographic fabrication. The holographic PNLC Fresnel lens also exhibits attractive electro-optical properties.     

Research on the Effect of Dielectric Barrier Discharge (DBD) Plasma Remote Treatment on Drag Force of Polyethylene Terephthalate (PET) Yarns in Air Flow with Different Humidities

In this paper, long-lived free radicals in atmospheric-pressure DBD plasma were used to treat PET yarn surface. Subsequently, the drag force of treated yarns in air flow at four humidities (40 ± 3, 50 ± 3, 60 ± 3, 70 ± 3%) was measured. The results suggest that with the increase of flow humidity, the air drag force of untreated yarn decreased while that of plasma-treated ones on average increased gradually. The average growth rates of the drag force under each humidity were 5.33, 7.58, 10.08 and 12.28% respectively. Meanwhile, the air drag force of the yarns treated at different specific input energy (SIE) densities and treatment time varied obviously under different flow humidity. The X-ray photoelectron spectroscopy analysis was performed to characterize the yarn surfaces chemically. The topology and roughness of PET yarns were measured by atomic force microscopy. The tensile test was carried out to characterize the mechanical strength. The ozone, nitrate and nitrite radicals and total organic carbon in tail gas of plasma were also analyzed. The maximal atomic concentration of N element on PET surface could reach 8.0%. The obtained results can improve the understanding of the property of long-lived reactive species from DBD plasma source generated at different SIE and the difference in PET surface etching and modification during remote treatment at different SIE. Moreover, the results also provide an experimental guideline for the improvement of weaving efficiency in air-jet weaving.     

粉煤灰基氧氟沙星分子印迹聚合物的制备及其应用

以工业废料粉煤灰微球为基质,氧氟沙星 (OFL) 为模板分子,采用表面印迹法制备印迹材料MIP。通过紫外光谱法结合理论分析选择实验条件,并对该印迹材料结构、吸附行为进行研究。结果表明,该印迹材料对氧氟沙星具有良好的特异识别性和优良的亲和性。与以硅胶为载体制备的印迹聚合物相比,该材料吸附容量更高和印迹效果更好。将其作为固相萃取填料对鸡产品进行分离富集,与C18柱相比,分离富集效果更好。结合UPLC,对实际样品中氧氟沙星进行分析,回收率为82.0%-96.7%,相对标准偏差低于5.5%,可用于鸡产品中氧氟沙星分离分析。